Hey guys, I have this constant problem and even the dealer doesn't know what is causing this issue: when I brake, especially in stop & go traffic, the CTT seems to lunge forward and make a heavy thud sound.. the only way I can describe it is like the suv is "jumping" when applying the brakes. I can actually feel the jump beneath the floor and the noise it makes is very noticeable. My advisor said that it could be associated with the spark plugs and engine coils, so I went ahead and replaced them, along with brand-new brake pads (front & rear), but the problem still remains. Any ideas on this? Thanks

 

first thing i would look at is the drivetrain...ie the propshaft bushes and the gearbox/transfer box (im presuming its an auto?)
does it "******" when you pull away fast?

or somthing could be loose under there??

get her on a rolling road pay for an hour (quite cheap) and brake etc and get someone/mechanic to look underneath ...this can simulate real road conditions without moving an inch.

 

it happens sometimes

 

it shouldnt....
your talking about a $$$$ car here?

 

I would say a mount... is it acting like a FWD car with a bad mount where you get a thud when you apply brakes or suddenly blip the throttle.. also check the drive shaft/ ujoint... especially with an early model...

 

Just to be safe, you're not driving with both feet are you? I've had a few strange issues where Cayenne owners were driving with both feet.

 

Hmm, I am also thinking that it is a drivetrain problem. But it doesn't occur often, and it is also very unpredictable (braking suddenly, braking slowly/normally). That is why the advisor tried to replicate it and couldn't pin-point what I was describing! Anyway, I will wait it out a bit more and see what is going on, and thanks for the replies guys.

 

Have them run TSB 3965, "Noise - from the area of the transfer case". I had a similar clunk that would happen just before stopping. I didn't need the transmission controller replaced, but the electric motor that operates the center diff had gone out.